Systemic oxygen extraction during exercise at high altitude

Systemic oxygen extraction during exercise at high altitude

Systemic oxygen extraction during exercise at high altitude

Background

Classic teaching suggests that diminished availability of oxygen leads to increased tissue oxygen extraction yet evidence to support this notion in the context of hypoxaemia, as opposed to anaemia or cardiac failure, is limited.

Methods

At 75 m above sea level, and after 7–8 days of acclimatization to 4559 m, systemic oxygen extraction [C(a?v)O2] was calculated in five participants at rest and at peak exercise. Absolute [C(a?v)O2] was calculated by subtracting central venous oxygen content (CcvO2) from arterial oxygen content (CaO2) in blood sampled from central venous and peripheral arterial catheters, respectively. Oxygen uptake (V.O2) was determined from expired gas analysis during exercise.

In acclimatized individuals at 4559 m, there was a decline in maximum absolute C(a?v)O2 during exercise but no alteration in OER calculated using central venous oxygen measurements. This suggests that oxygen extraction may have become limited after exposure to 7–8 days of hypoxaemia.

Abstract

Background

Classic teaching suggests that diminished availability of oxygen leads to increased tissue oxygen extraction yet evidence to support this notion in the context of hypoxaemia, as opposed to anaemia or cardiac failure, is limited.

Methods

At 75 m above sea level, and after 7–8 days of acclimatization to 4559 m, systemic oxygen extraction [C(a?v)O2] was calculated in five participants at rest and at peak exercise. Absolute [C(a?v)O2] was calculated by subtracting central venous oxygen content (CcvO2) from arterial oxygen content (CaO2) in blood sampled from central venous and peripheral arterial catheters, respectively. Oxygen uptake (V.O2) was determined from expired gas analysis during exercise.

In acclimatized individuals at 4559 m, there was a decline in maximum absolute C(a?v)O2 during exercise but no alteration in OER calculated using central venous oxygen measurements. This suggests that oxygen extraction may have become limited after exposure to 7–8 days of hypoxaemia.